Each country has its own laws/rules. I defy anyone to take pesos, Euros rubles, or Canadian dollars to their grocery store and try to pay for their groceries with it. Not going to happen.
True - but there is a difference. The dollar is the world currency. There are many nations where they prefer dollars. Not as much as it used to be, but...
I guarantee you there are places in America where they will take the peso or loonie (is that how you write it?)